WASHINGTON (CNN) --Senior U.S. Justice Department officials have strongly defended their controversial program requiring tens of thousands of men visiting from mostly Muslim nations to register with immigration authorities.

The National Security Entry-Exit Registration System (NSEERS) for targeted populations entering the United States has directly identified suspected terrorists, they said.

The officials, requesting anonymity, said immigration authorities have fingerprinted and processed more than 54,000 aliens, and detained 330 of them on a wide range of criminal violations, since last fall.

In addition, 23,414 men already in the United States from the list of selected countries have stepped forward for registration on the domestic program. Of 1,169 men who were detained at least temporarily, only 164 currently remain in custody officials said.

One senior official said the program had "stopped and identified terrorists," but refused to say how many suspected terrorists had been detained, and acknowledged no one had been charged with a terrorism-related crime to date.

Immigration officials privately acknowledge some surprise that despite public complaints and scattered protests, the number of visitors from specified countries agreeing to the domestic registration has slightly exceeded the estimated numbers of individuals the government believed were in the United States and covered by the program.

Earlier Thursday, Attorney General John Ashcroft formally announced the entrance-exit registration was being expanded to include all men over 16 years of age from Egypt, Jordan, Kuwait, Indonesia and Bangladesh.

That notice, the fourth such list of nations announced, is expected to prompt about 19,000 male citizens of those countries to appear at one of the 76 INS offices around the nation during the registration period which runs from February 14 through March 28.

The first notice went to visitors from five officially declared terrorist states -- Iran, Iraq, Syria, North Korea and Sudan. Three thousand individuals registered. The Iranian community in California was the center of protests and complaints about the requirement, and the hundreds who were detained for visa overstays and other immigration violations.

Officials Thursday insisted most of the detentions were temporary as federal agencies conducted criminal records checks, and determined flight risk. Justice officials insisted most of those detained were released in less than 24 hours.

Global reach

The second notice went to men from Afghanistan, Algeria, Bahrain, Eritrea, Lebanon, Morocco, Oman, Qatar, Somalia, Tunisia, United Arab Emirates and Yemen. That led to 7,200 registrations.

Authorities emphasized that the border registrations are extended to individuals from nearly every country on the globe if intelligence indicates they represent a possible threat.

One top official pointed to a series of arrests stemming from the program as proof the counterterrorism effort is working. He said a Tunisian man was arrested when records showed he had been convicted of multiple drug offenses. A Dominican Republic citizen was arrested for assault and burglaries. Officials said 15 felons were arrested among the Iranians who registered.

And in one case, an individual from Saudi Arabia was taken into custody in Florida where he was taking flight training and attempted to avoid registering in the prescribed time.